Long term evolution (LTE) proposed by the 3rd Generation Partnership Project (3GPP) is the largest new technology R&D project of the 3GPP in the recent two years. The LTE project focuses on the orthogonal frequency division multiple access (OFDMA) and multi-input multi-output (MIMO) technologies. The main performance objectives of the 3GPP LTE project include: a downlink rate of 100 Mbps and a peak uplink rate of 50 Mbps can be provided at a 20 MHz spectral bandwidth, and may be used to improve the performance of cell edge users, so as to increase the cell capacity and reduce the system delay. When the internal unidirectional transmission delay of the user plane is shorter than 5 ms, it takes the control plane less than 50 ms to transition from the sleep state to the active state, and less than 100 ms to transition from the camping state to the active state. In addition, a cell coverage with the radius of 100 km may be supported; over 100 kbps access services can be provided for users who move at the speed of 350 km/h; paired or unpaired spectrums can also be supported; and various bandwidths ranging from 1.25 MHz to 20 MHz may be flexibly configured.
To support a higher system bandwidth and achieve larger capacity and higher spectrum efficiency, the LTE-advanced (LTE-A) system introduces an important feature, that is, carrier aggregation (CA). CA depends on the terminal capability, service requirement, and network configuration. CA may be CA of continuous spectrums or CA of discontinuous spectrums. The bandwidths aggregated by CA may be the same or different, for example, the aggregation of 5 MHz and 10 MHz.
The LTE-A system is evolved from the LTE system and also represents the evolution direction of communication systems in the future. To implement the evolution from the 802.16e system to the time division duplex (TDD) LTE-A system, one carrier may be used to carry 802.16e system, and another carrier may be used to carry TDD LTE-A. The 16e system needs to occupy a carrier even if there are only few users in the 802.16e system, thereby causing a waste of resources. To reduce the waste of resources, the physical layer of the 16e system may be integrated with the physical layer of the TDD LTE-A system. However, because the TDD LTE-A system cannot satisfy the synchronous transceiving requirement on the entire network, large interference may occur between systems, so that the systems cannot work normally.